1. Field of the Invention
The invention relates to a device for turning up the tire sidewalls on a tire building drum with devices for shaping a tire carcass, whereby the tire building drum features two lever systems arranged essentially and/or generally symmetrically to the drum center, which lever systems are each connected to a lever supporting body in a pivoted manner, whereby the two lever supporting bodies can be moved in the axial direction of the tire building drum.
2. Discussion of Background Information
In the conventional production of new tires, one production step takes place on a tire building drum, in which the tire carcass at first resting flat is shaped by an expansion process. The actual shaping process of the carcass takes place, e.g., via a middle bellows that expands the central area of the carcass. In this process the two outer sidewalls are subsequently turned up on the shaped carcass and thereby folded about the bead core. This process of turning up the tire sidewalls takes place either with so-called side shaping bellows or with a roller lever system arranged in a rim-shaped manner over the circumference. When side shaping bellows are used, two inflating bellows arranged in the area of the sidewall layers are inflated, which inflating bellows in this manner press the sidewalls onto the shaped carcass. The turning up process with the aid of side shaping bellows can have the disadvantage that these bellows do not act all the way up to the shoulder areas of the green tire, making manual finishing operation necessary. Furthermore, the side shaping bellows are subject to a high wear, making necessary a correspondingly frequent replacement, which is associated with a high expenditure of time.
Turning up sidewalls with the aid of a roller lever system is disclosed, e.g., in DE 199 34 791 C1. With this device the spreading apart of the roller lever system takes place via a pneumatic drive that comprises two separate pneumatic cylinders. The two pneumatic cylinders are acted on separately with compressed air, spreading apart the tire lever system and turning up the sidewalls on the carcass.
A major disadvantage with this principle is that, e.g., due to different frictional effects, the spreading apart of the opposite tire lever systems does not always occur simultaneously or suddenly. The consequence of the two roller lever systems being spread apart at different times is that the sidewalls are not pressed uniformly against the shaped carcass and a defective connection between the two material layers thus occurs, which in turn can lead to tire wastage.